This pair of before (June) and after (Dec) aerial photos from the bayside eastern shore of Maryland shows the seagrass die-back observed by VIMS researchers throughout the lower Bay during the very warm summer of 2005.

This pair of before (June) and after (Dec) aerial photos from the bayside eastern shore of Maryland clearly shows the seagrass die-back observed by VIMS researchers throughout the lower Bay during the very warm summer of 2005.

VIMS researcher collects flowering shoots from eelgrass plants. The seeds will be used for restoration.

Fruits of the eelgrass Zostera marina. Each fruit is about the size of a rice grain.

Seeds of the eelgrass Zostera marina. Each seed is smaller than a rice grain.

SAV researcher Scott Marion helps eelgrass seeds drop from flowering shoots for later collection. The seeds will be used for restoration.

The reintroduction of eelgrass into Virginia’s coastal
bays—a collaborative effort among the Virginia Institute of Marine Science, the
University of Virginia, The Nature Conservancy, and the Virginia Coastal Zone Management Program—is one of the great success
stories in the annals of marine restoration.

This week, a special theme section of the leading journal Marine Ecology Progress Series features 9
articles that describe the 15-year restoration process and explain how the resulting
“state change” from bare seafloor sediments to lush eelgrass meadows has led to
a healthier and more vibrant ecosystem overall. A final article, however, cautions
that the restored meadows are vulnerable to global warming.

Eelgrass—one of several local species of submerged flowering
plants—flourished in the seaside bays of Virginia’s Eastern Shore until the 1930s,
when a wasting disease and the passage of a large hurricane wiped them out.
When eelgrass disappeared, so too did the food and nursery habitat that they had
provided to numerous marine organisms and seabirds. One notable loss was the
bay scallop—which until that time had supported a significant commercial
fishery.

First, the bays are part of the Virginia Coast Reserve. Managed
by The Nature Conservancy, the reserve has been under intensive study since
1987 as a Long Term Ecological Research (LTER) site administered by the
University of Virginia. That’s important, says Orth, because “Ongoing baseline
studies by LTER scientists in the absence of eelgrass set the stage for
understanding the subsequent ecological benefits of restoring eelgrass as a
dominant species.”

Second, the reserve’s relatively pristine waters are a major
reason for the success of the eelgrass restoration effort. “These bays are
unique in that they receive little impact from human activities,” says Orth. “Data
from the LTER show that they receive low levels of nutrient pollution from the
surrounding watershed, and that water quality and clarity has remained high over
the last two decades.” Clear water is key for transmitting the sunlight that
seagrasses need to thrive.

Coastal Bays vs. Chesapeake Bay

VIMS professor Ken Moore and colleagues contribute to the
theme section with a comparative study that expands on the link between water quality
and eelgrass abundance. Their results show that the increased abundance of eelgrass
in the pristine waters of the coastal bays is countered by decreased or static
abundance in nearby areas of lower Chesapeake Bay where waters are less clear
and warmer during the summer.

Moore says “Our data show that a combination of factors in
the coastal bays—including cooler summertime water temperatures and lower light
attenuation—interact to both increase the proportion of light available for eelgrass
photosynthesis, and to decrease the amount of light the plants need to meet
their metabolic requirements through photosynthesis.”

Ecosystem services

Other papers in the theme section report on studies led by
Karen McGlathery and Matthew Reidenbach of the University of Virginia. These
show that restoration of eelgrass to the coastal bays has led to recovery of
key “ecosystem services,” including increased capture of solar energy and
subsequent transfer up the food chain, greater removal of polluting nutrients,
and more trapping of suspended sediments. The latter leads to clearer water,
which in turn further stimulates eelgrass growth.

Overall, these studies reveal that the increase in ecosystem
services shows no sign of leveling off— even after nine years of eelgrass
recovery—thereby suggesting that full restoration has not yet been reached. This
optimistic finding is tempered by a modeling study led by UVA’s Joel Carr,
which indicates that the eelgrass meadows “have limited resilience to increases
in water temperature predicted from current climate change models.” That
conclusion is bolstered by Moore’s field-based study, which shows that
eelgrasses are already stressed in Chesapeake Bay by recent summertime heat
waves.

Restoration history and funding

Orth and his team began planting eelgrass seeds and shoots
into Virginia’s coastal bays in 1997, a year after hearing an anecdotal report
of a small eelgrass patch in South Bay. From 1999 through 2010, VIMS and UVA staff
and Nature Conservancy volunteers have collected and broadcast 37.8 million
eelgrass seeds across 309 acres in 4 coastal bays. Those plantings have now
expanded through natural re-seeding into 4,200 acres of lush eelgrass meadow.

The 15-year effort has been funded by the grants from numerous agencies, notably the Coastal Programs of the Virginia Department of Environmental Quality (administered by NOAA’s Office of Ocean and Coastal Resource Management), the Virginia Recreational Fishing License Fund, the American Recovery and Reinvestment Act, The Nature Conservancy, the U.S. Army Corps of Engineers, the Virginia Department of Transportation, and private grants from the Allied-Signal Foundation, Norfolk-Southern, and the Keith Campbell Foundation for the Environment.